1. Field of the Invention
This invention relates to a melting furnace for melting a cold charge in an efficient manner.
2. Prior Art
One conventional melting furnace 50 shown in FIG. 1 includes a body 52 which comprises a heating portion 54 of a rectangular cross-section defined by a pair of side walls 54a and 54b, a pair of end walls (not shown) interconnecting the sides walls 54a and 54b at their opposite ends, an upper wall 54c and a bottom wall 54d and a melting portion 56 of a channel-shaped cross-section disposed adjacent to the heating portion 54 and defined by the side wall 54a, an outer side wall 56a, a pair of end walls (not shown) interconnecting the side walls 54a and 56a at their opposite ends, and a bottom wall 56c extending from the bottom wall 54d in coplanar relation thereto. The melting portion 56 has an open top 55 serving as a material-feed means through which a cold charge or metal to be melted is fed to the melting portion 56. Burners (not shown) serving as heating means are provided with their nozzles extending through the side wall 54b of the heating portion 54 for maintaining the interior of the heating portion 54 at elevated temperatures, so that the molten metal 58 in the heating portion 54 is not subjected to a temperature drop. An electromagnetic agitator 60 is mounted below the bottom wall 54d of the heating portion 54 for agitating the molten metal 58 in the heating portion 54 so as to keep a temperature thereof uniform over the entire area of the heating portion 54. The melting portion 56 communicates with the heating portion 54 via a port 62 formed through the side wall 54a. A vertically-movable gate or plate 64 is mounted on the side wall 54a with its lower end always kept dipped in the molten metal 58 to a certain extent for closing an upper end portion of the port 62. The gate 64 is moved vertically so that the lower end of the gate 64 is always dipped in the molten metal 58 to a predetermined degree. The gate 64 prevents impurities or whitewash, floating on the top of the molten metal 58 in the melting portion 56, from intruding into the heating portion 54. The heat of the heating portion 54 is fed to the melting portion 56 via the molten metal 58, flowing through the port 62, for melting a cold charge introduced into the melting portion 54 from the open top 55.
Since there is provided only one port 62 which communicates the melting portion 56 with the heating portion 54, the molten metal 58 agitated by the electromagnetic agitator 60 in the heating portion 54 flows into the melting portion 56 through the port 62 and then is returned to the heating portion 54 through the port 62. Thus, the flow of the molten metal 58 into the melting portion 56 tends to be cancelled by the flow of the molten metal 58 from the melting portion 56, so that the molten metal 58 of elevated temperatures in the heating portion 54 may not reach every corner portion of the melting portion 56, which results in failure to efficiently melt the cold charge fed to the melting portion 56.